This invention relates generally to refrigerator cabinets, and more particularly to cabinets for refrigerators having two compartments, one above the other, separated by a partition.
A common arrangement for a household refrigerator provides two separate compartments, one above the other, in which the upper compartment usually serves as a frozen food compartment, while the lower compartment is maintained at a temperature slightly above freezing for best preservation of fresh foods. Each of these compartments has its own door mounted on hinges secured to the cabinet, and has a magnetic sealing gasket around its periphery which must engage with a smooth magnetic surface around each of the separate food compartments. Because of space considerations, such refrigerators are built in the form of a rectangular box having a height that is more than twice the width of the cabinet, while the freezer compartment has a volume of approximately half the volume of the fresh food compartment.
A common construction for refrigerators of this type is to use a relatively thin metal outer shell forming the exterior surfaces of the cabinet and this shell forms a flange around the front face to provide for engagement with the sealing gaskets carried by the doors. The interior is formed from a one-piece liner thermoformed from a sheet of thermoplastic. The liner has a peripheral flange at the front edge and the liner is mounted within the shell by the flange which seats into a groove on the shell directly behind the front face. When the space between the liner and the shell is filled with an insulating, rigid foam, such as polyurethane foam, the result is a generally rigid and strong cabinet because of the sandwich construction even though the shell and the liner, by themselves, may not have a great deal of rigidity.
To separate the two compartments a partition, which includes insulating material, is mounted in the liner and generally held in place vertically by projecting horizontal ribs or grooves formed within the liner so that the partition can be supported around the three sides in engagement with the cabinet liner. This arrangement requires the use of a mullion assembly which extends between the two sides of the shell in line with the partition, and which provides a plurality of functions, including those of holding the partition in place, providing a tension strap between the opposed sides of the cabinet to prevent them from bowing outwardly, providing a finished surface for seating of the magnetic gaskets along the adjacent door edges, and for providing a strong mount for a hinge assembly bracket which provides the lower hinge point for the upper door and the upper hinge point for the lower door.
The mullion construction used for these refrigerators generally includes at least a mullion cover fabricated from the same material as that used for the shell to provide uniformity of appearance, together with a supporting structure to provide a mounting for the mullion cover and the other structural requirements of the refrigerator cabinet. A particular problem with this mullion support structure is that it must be firmly anchored at each end to the cabinet shell to give the structure sufficient strength and rigidity in tying together the side walls and providing the necessary support for the hinge bracket, which is generally so constructed that it may be mounted on either side to provide for reversibility of the refrigerator doors.
One particular problem on the mounting of the support structure is that the actual opening into the interior of the refrigerator is determined by the width between the edges of the faces on the cabinet shell. Thus, these faces are made as narrow as possible, but a certain minimum width must be maintained, since it is necessary that the mullion support make engagement with or be fastened to portions of the shell behind the front face. One approach to thIs is to mount suitable support brackets on the shell prior to the foaming operation so that their brackets are embedded in the foam. These brackets can then provide a mounting for the mullion support assembly that is no longer than the width between the edges of the cabinet face. Such arrangements are shown in U.S. Pat. Nos. 4,550,576; 4,765,696; and 4,801,181.
Another approach as shown in U.S. Pat. Nos. 4,606,112; 4,632,470; and 4,706,363 is to use a mullion support strap that is formed in two pieces with an overlapping or telescoping joint at the center which allows the mullion support strap to be shortened for insertion behind the front face, after which it can be lengthened so that each end hooks behind the front face of the shell for attachment to the shell or a recessed bracket, after which the two pieces of the mullion support are firmly secured together by clamping bolts at the connection.
A particular problem with both of the above approaches is that because they require a plurality of parts, some of which may have to be installed prior to the foaming operation and some after it, the multiplicity of parts and labor to install them results in a rather high-cost construction.
Another approach has been to use a mullion support strap that is flat and is able to flex in a horizontal plane so that the center may be bowed out to shorten the distance between the ends so that it may be slipped behind the edges of the front face of the cabinet shell, and afterwards secured in place. One such arrangement is shown in U.S. Pat. No. 4,558,503, and a study of this patent shows the difficulties in assembling this type of arrangement.
Another approach has been used over a period of time by the assignee of the present application, in which a flat strap of relatively thick steel was inserted after the partition was assembled within the liner by bowing out the center section of the strap and inserting each of the ends into the groove holding the liner flange in front of the liner flange so that its front face abuts directly against the re-entrant folded wall of the shell directly behind the front face. A screw then extends through a hole in the front face and the reentrant flange to make threaded engagement directly with a threaded opening on the strap. The mullion face is then attached directly to the strap by means of a screw at each end of the face extending through the mullion face and threadedly engaging the support strap. On the side of the refrigerator on which the doors are to be hinged, the same two screws are also used to mount a hinge support bracket that serves as the lower hinge for the upper door and the upper hinge for the lower door. While this arrangement provides sufficient tensile strength to prevent the edges or sides of the cabinet shell from bowing outwardly, it tends to allow excessive flexing of the hinge support bracket, since the support strap must be thin enough to allow sufficient flexing during assembly.